Network content management

ABSTRACT

One embodiment of an inventive networking environment includes clients called sending clients because they send network content through a network, and clients called receiving clients because they receive the network content from the sending clients through the network. Both sending clients and receiving clients are “clients” in that they rely on a management server to orchestrate the secure transfer of information from sending clients to receiving clients.

RELATED CASES

U.S. application Ser. No. ______, filed on Apr. 7, 2000, titled“Ticketing and Keying for Orchestrating Distribution of NetworkContent”, (attorney docket number 4698.P002), and

U.S. application Ser. No. ______, filed on Apr. 7, 2000, titled “NetworkCommunications Security Agent”, (attorney docket number 4698.P001).

FIELD OF THE INVENTION

The present invention pertains to the field of networking. Moreparticularly, this invention relates to distribution of network content.

BACKGROUND OF THE INVENTION

Traditional approaches to network content management are widely usedtoday by a variety of entities such as pay television providers,corporate networks, and members only Internet websites. Thesetraditional approaches usually rely on maintaining groups of users whoare eligible to receive certain content. Many different kinds ofrelationships and security schemes are used to associate users andcontent. For instance, a corporate network may include several differentgroups of users who are eligible to access different groups of contentbased on job description and need to know. A vice president ofcorporation finance may belong to one group of users that has access tofinancial files, and an engineer may belong to another group of usersthat has access to a completely separate set of purely technical files.All of the corporate users may belong to yet another group of users thathas access to general corporate information like a community bulletinboard, a schedule of company social events, etc. Depending on who a useris, the user may or may not have authority to read, write, execute,and/or delete content stored in a file structure on the network.

In a pay television network, certain viewers will have purchased onlythe basic television channels and other users will have purchased one ormore premium channels or packages of channels, such as sports packagesfor particular professional teams. Channels that a viewer has not paidfor are generally scrambled. With potentially hundreds of thousand oreven millions of viewers, and potentially hundreds of different channelpackages, the associations and security controls among viewers andcontent are likely to be very complex.

As the number of users on a network increases, and as the volume ofcontent distributed over the network increases, managing thedistribution of content becomes more difficult. This is particularlytrue as networks become more interactive and more dynamic. The Internetprovides a good example of a difficult network to manage. The size ofthe Internet and the dynamic nature of the Internet make contentmanagement particularly challenging.

The number of people and organizations connected to the Internetcontinues to increase virtually every day. At the same time, the volumeof information available on the Internet continues to increase. Peoplecan add new content, delete content, decide to access different content,search for new content, etc., on the spur of the moment. A contentprovider never knows what to expect. If a content provider attracts toomuch attention, the provider can become overwhelmed with traffic,essentially shutting down the provider. On the other hand, a contentprovider can easily become lost in the vast virtual expense of theInternet and receive very little traffic if any at all.

As the Internet and broadcast services merge, the content managementchallenges will continue to increase. For instance, for an existing paytelevision network, the number of users and volume of content is likelyto be large, but the content and user groups are comparatively static.That is, the pay television provider can usually predict what televisionchannels it is going to provide, and the typical user probably will notchange his or her package of channels very often. Changes to content anduser groups can be managed over the course of days or weeks.

In an Internet environment, however, the dynamic nature of user groupsand content could drastically change. An Internet-based pay televisionservice could be entirely pay-per-view, resulting in huge fluctuationsin the number of users. For instance, the release of a particularlypopular movie could attract too many viewers and shut down the contentserver. Multicasting can alleviate some of the difficulties with networkcontent that is in high demand by transmitting a data stream thatviewers can simply pick up in the network, analogous to a broadcasttelevision signal from an antenna. Providing security for a multicast,however, provides additional changes. A large number of viewers may wantto access the content, and each viewer will generally need to obtain adecryption key from the content provider in order to make use of thedata stream. A large number of requests for decryption keys canoverwhelm a server just like a large number of requests for any otherkind of data.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of the present invention are illustrated in the accompanyingdrawings. The accompanying drawings, however, do not limit the scope ofthe present invention. Similar references in the drawings indicatesimilar elements.

FIG. 1 illustrates one embodiment of a network environment.

FIG. 2 demonstrates one embodiment of a ticket server.

FIG. 3 illustrates one embodiment of a database.

FIG. 4 illustrates one embodiment of a ticket.

FIG. 5 demonstrates one embodiment of a key server.

FIG. 6 illustrates event intervals and associated key server load.

FIG. 7 illustrates event intervals and associated key server load.

FIG. 8 demonstrates one embodiment of a key server.

FIG. 9 demonstrates one embodiment of a client.

FIG. 10 demonstrates one embodiment of a management server.

FIG. 11 illustrates one embodiment of a management server.

FIG. 12 demonstrates one embodiment of a security agent.

FIG. 13 illustrates one embodiment of a security agent.

FIG. 14 illustrates one embodiment of a hardware system.

FIG. 15 illustrates one embodiment of a machine readable storage medium.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the presentinvention. However, those skilled in the art will understand that thepresent invention may be practiced without these specific details, thatthe present invention is not limited to the depicted embodiments, andthat the present invention may be practiced in a variety of alternateembodiments. In other instances, well known methods, procedures,components, and circuits have not been described in detail.

Parts of the description will be presented using terminology commonlyemployed by those skilled in the art to convey the substance of theirwork to others skilled in the art. Also, parts of the description willbe presented in terms of operations performed through the execution ofprogramming instructions. As well understood by those skilled in theart, these operations often take the form of electrical, magnetic, oroptical signals capable of being stored, transferred, combined, andotherwise manipulated through, for instance, electrical components.

Various operations will be described as multiple discrete stepsperformed in turn in a manner that is helpful in understanding thepresent invention. However, the order of description should not beconstrued as to imply that these operations are necessarily performed inthe order they are presented, or even order dependent. Lastly, repeatedusage of the phrase “in one embodiment” does not necessarily refer tothe same embodiment, although it may.

The networking environment described below embodies a number ofinventions for improving network content management. Embodiments of oneinvention are claimed in the present patent and embodiments of otherinventions are claimed in the related patents.

FIG. 1 illustrates one embodiment of the inventive networkingenvironment. Clients 110 are called sending clients because they sendnetwork content through network 150. Clients 120 are called receivingclients because they receive the network content from the sendingclients through network 150. Both sending clients 110 and receivingclients 120 are “clients” in that they rely on management server 160 toorchestrate the secure transfer of information from sending clients 110to receiving clients 120.

Relying on management server 160 to orchestrate content managementprovides numerous advantages. One advantage in particular is thatmanaging access to content at a server reduces the volume of datatraffic on individual clients.

Management server 160 includes ticket server 130 and key server 140 Inthe illustrated embodiment, management server 160 is shown in dottedlines because ticket server 130 and key server 140 need not be locatedtogether. That is, key server 140 and ticket server 130 can be locatedat separate locations and on separate machines. In various embodiments,as discussed below, key server 140 may be located in a secure locationto reduce the likelihood of tampering with keying information.

Network content can represent any form of data, including data files,multicast data, multimedia data, interactive data, etc. Network contentwill usually be referred to herein as events or sessions. Examples ofevents are a multicast presentation of a feature length movie, providingaccess to a file, and providing access to an interactive gamingenvironment.

In one embodiment, network 150 represents the Internet. In alternateembodiments, network 150 represents a private or corporate network.

Various embodiments of the inventive networking environment areparticularly suited for multicasting events, although they work well forunicast events too. Multicasting is a data transmission from one sendingclient 110 to multiple receiving clients 120. Each client accessesticket server 130 to be authorized for the event. If a client isauthorized, it will learn when and where a multicast event will occur aswell as where to go to get a security key to participate in the event.In the illustrated embodiment, each client is instructed to get thesecurity key from key server 140. Alternate embodiments may includeseveral different key servers 140 located throughout network 150, andeach key server may be associated with different events or sets ofevents in order to distribute the server load for key requests.

Around the time a multicast event is supposed to start, each authorizedclient accesses key server 140 to obtain a key for the event. In oneembodiment, the key is a “symmetric” cryptographic key. A key is“symmetric” in that both the sending client and the receiving client usethe same key. When the event actually begins, the sending client usesthe key to encrypt the multicast and each receiving client uses the keyto decrypt it.

FIG. 2 demonstrates one inventive embodiment of ticket server 130 ingreater detail. As with all of the described figures, certainembodiments may include less elements, combine one or more elements,change the order of elements, and/or add to the elements shown in FIG.2. In the illustrated embodiment however, the ticket server receives arequest in block 210 from a client and in block 220 determines if theclient is registered. In one embodiment, determining if the client isregistered involves accessing a database of registered clients to see ifthe client appears in the database. This could include requiring theclient to provide a login name and a password or some other verificationsuch as a smart card. As discussed below, the request may actually passthrough one or more stages of application specific client care handlingbefore reaching ticket server 130. In which case, a client careapplication may determine whether or not a client is registered ratherthan ticketing server 130. In any case, if the client is not registered,the client is prevented from proceeding.

In block 230, the ticket server accesses a database. The databasedefines associations between registered users and events. Skippingbriefly to FIG. 3, one embodiment of a database is illustrated. Theillustrated database represents a directed acyclic graph of groups. Eachgroup, G1 through G6, has assigned to it one or more events and clients.For instance, event E1 and client C1 are assigned to group G1. Eachclient assigned to a group is associated with all of the events assignedto the group. For instance, client C1 is associated with event E1.Client C1 is likely to be a sending client that can send event E1.

The database is directed and hierarchical in that clients are not onlyassociated with events assigned to the group, but are also associatedwith events assigned to “ancestor” groups. An ancestor group is a groupat a higher level of the hierarchy from which a current group depends.The directed nature of the database is indicated by the arrows. Groupassociations follow the direction of the arrows. From a given group,associated events can be accumulated by backtracking up the arrows tothe root node. For instance, client C7 is assigned to group G6 so clientC7 is associated with events E7 and E8 because they are assigned to thesame group. Backtracking the arrow up to group G4, client C7 is alsoassociated with event E5, and continuing up to root group G1, client C7is also associated with event E1.

An association can apply either for sending or receiving an event. Thatis, with respect to one event, a client may be a sending client, andwith respect to another event, a client may be a receiving client.

Using a database such as the one described in FIG. 3, a summary ofevents to which a client is associated can be quickly constructed byfollowing the flow directed hierarchy.

Returning to FIG. 2, in block 240, ticket server 130 locates a group towhich the client is assigned and all ancestor groups. Based on thelocated groups, ticket server 130 constructs a summary of eventsassociated with the client in block 250. As events are identified in theassociated groups, information identifying each event is added to thesummary.

Skipping briefly to FIG. 4, one embodiment of a ticket is illustrated.The illustrated ticket includes a group identifier 410. In oneembodiment, all clients associated with the same group are given thesame ticket. Below the group identifier, the ticket includes a list 420of all the events, 1 through N, associated with the identified group.Each event is identified by title information 421, and each eventsummary includes an internet protocol (IP) address of the sending client422 for the particular event, a time indication 423 for the particularevent, and an IP address for the key server 424 that stores theencryption keys for the particular event. Alternate embodiments mayinclude another IP destination address which in the multicast case is anIP Multicast Group address. Where all of the clients associated with agiven group get the same address, a sending client will likely see itsown IP address in that field. The time indicator can be a fairly complexexpression. For instance, the event could repeat on a daily or weeklybasis, or on certain days of the month or year.

In addition to group identifier 410 and list 420, the illustrated ticketincludes digital certificate 430. Digital certificate 430 may include adigital “hash” of list 420 and may certify that the client is authorizedto access a key for any of the listed events. In alternate embodiments,different digital certificates can be used for each event in list 420.

Returning again to FIG. 2, in block 260, ticket server 130 transmits theticket, including the summary of associated clients to the client. Asdiscussed below, a client handling system may operate between the ticketserver and the actual client. In which case, ticket server 130 shouldtransmit the ticket to the client through the client handling system.

Ticket server 130 provides a convenient way for clients to see whichevents are available. In alternate embodiments, in addition to or inplace of providing tickets in response to requests, ticket server 130may be configured to issue tickets under certain circumstances. Forinstance, for each client or for selected clients, ticket server 130 mayissue tickets on a regular basis and/or whenever associated eventschange. Additionally, events could be prioritized based, for instance,on to which group an event is assigned. In which case, depending on thepriority of a particular event, ticket server 130 may or may not issue aticket to one or more clients based on a change in the event.

Turning now to FIG. 5, one inventive embodiment of key server 140 isdemonstrated. In block 505, an initial request for a key is receivedfrom a client. The initial request is received at a randomly generatedinstant in time during a predetermined period before the start of theevent. For instance, skipping briefly to FIG. 6, the timing of oneembodiment of, an event is illustrated. The event will begin at theevent start time 610. The predetermined period before the event starttime 610 is the initial keying period 620. The request is received atsome instant in time during the initial keying period 620, and theinstant in time is randomly generated by the client.

In alternate embodiments, a client may access the event late. In whichcase, the initial request may not be received during the initial keyingperiod 620. If a client accesses an event late, the first part of theevent may not be accessible until the client receives a key.

Referring back to FIG. 5, in block 510, key server 140 establishes apoint-to-point secure link with the client. In block 515, key server 140verifies the clients credentials which are included in the request fromthe ticket. Any number of secure link protocols can be used, eitherinitiated by key server 140 or the client that issued the request.

In block 520, an initial key is transmitted to the client. In theillustrated embodiment, the key includes a symmetric cryptographic keyas discussed above. That is, both the sending and receiving clients usethe same key to encrypt and decrypt. In addition to the cryptographickey, the illustrated embodiment includes an initiation time for the keyand a life time for the key after the key is initiated.

The initiation time and life time for the key are more important for asending client. This is because the key server and the sending clientneed to coordinate or synchronize which keys are made available toreceiving clients and when. Therefore, a sending client and a serverneed to have somewhat synchronized clocks. Any number of techniques canbe used to synchronize the time of day between the key server and thesending client.

A receiving client, in contrast, can just implement a key as soon as thekey is received. Or, if a received key is not yet in use when the key isreceived, a receiving client can simply store the key until the keycomes into use. Any number of techniques can be used to age a stored keyso that it is not stored indefinitely if for some reason an eventcorresponding to the key never initiates.

In block 525, a refresh request is received. Refreshing involveschanging keys after a certain duration. Refreshing, also referred to asre-keying, severs at least two purposes. First, for cryptographicreasons, it is a good idea to change keys from time to time. The longera key is used, the more likely it is that someone will be able to crackthe key and access the event without authorization. The more often keysare changed, the better the security.

A second purpose for refreshing is access revocation. That is, if a userstops being authorized to access an event part way through the event,the next time the key is refreshed for the event, the key server canprevent the user from having future access by not sending the refreshkey. For example, the event may be a continuous stream, like a multicastof an all news pay television station. Keys may be refreshed at one hourintervals. If, at some point in time, a receiving client fails to payhis bill, a client care system may recognize the missed payment and senda notification to the key server indicating that the client is no longerauthorized. In response to which the key server can withhold the nextrefresh key, effectively revoking access. For instance, referring againto FIG. 6, the event starts at event start time 610. At the end of eachevent interval 630, the client switches to a new key retrieved from thekey server.

As illustrated in FIG. 6, the event interval 630 is also the forwardsecurity window for the next event interval 630. That is, while theclient is sending or receiving content using the current key during thecurrent event interval, the client also accesses the key server duringthe forward security window to get the next refresh key. In alternateembodiments, the event interval and the forward security window do notexactly coincide. That is, the forward security window may be shorter orlonger than the event interval, and the client may retrieve keys fromthe key server more than one event internal in advance.

Referring back to FIG. 5, still with reference to block 525, the refreshrequest is received at some random point in time during the forwardsecurity window. That is, the client generates a random access timeduring the first forward security window, and then advances the time bythe duration of the event interval for each subsequent event interval.In this way, a given client will access the key server at a particularpoint in time with respect to the beginning of each event interval. Inalternate embodiments, the client randomly generates a new access timefor each forward security window.

By randomly distributing requests over the course of the event interval,the load on the key server when several clients are accessing the eventis distributed over the course of the event interval. Similarly, therandom instant in time during the initial keying period 620, in FIG. 6,during which the client requests the initial key, is intended todistribute the load on the key server over a period of time when manyclients are accessing the key server at roughly the same time.

Distributing server load of the event intervals for refresh keys tendsto work well. Unfortunately, as illustrated in FIG. 6, distributing afirst request for an initial key when many requests are being processedis not always successful. Many human users of client systems are proneto wait until the last minute before the beginning of an event to try toaccess keys for the event. These last minute user can cause a peak 650in the key server load 640, potentially overwhelming the key server.

Various embodiments of clients include agents for automaticallyaccessing the key server at a random time during the initial keyingperiod, but unless the human user has the machine turned on so that theagent can operate, no request will be made. For instance, home users areless likely to leave their machines turned on than business users. Homeusers are more likely to turn their machines on just moments before anevent. Business users will probably not experience potential problemslike peak 650 since business users often leave their machines on,allowing automatic client agents to perform the initial keying.

FIG. 7 illustrates an embodiment of an alternate inventive approach toinitial keying. In FIG. 7, the first interval after the event starts isnot encrypted so that last-minute clients can begin watching the event.Any time during the extended initial keying period 710 a client canaccess the key server and retrieve the initial key. By allowing accessto the first interval unencrypted, the load 730 on the key server isflattened out somewhat, reducing the peak load 720 compared to theapproach described in FIG. 6. In alternate embodiments, more than oneinterval could be transmitted without encryption, or a first unencryptedinterval could be longer or shorter than the rest of the eventintervals.

Referring back once again to FIG. 5, now with reference to block 530,the key server checks to see if the client is still authorized. If theclient is not authorized, the refresh key is not sent or, in anotherembodiment, not all of the necessary information is included in therefresh key that is sent to the client to effective revoke access. Ifthe client is still authorized, the key server determines which key tosend based on the current time in block 540. That is, as discussedabove, for a sending client, the key server and the sending client needto be fairly closely synchronized in time so that the key server canprovide the correct keys at the correct time.

In block 550, the key server and the client establish a point-to-pointsecure link and verify credentials. In block 560, the key serverprovides the refresh key over the secure link. In block 570, if there isanother event interval, the process returns to block 525 to wait for thenext refresh request. If there are no additional event intervals afterthe current one in block 570, the process ends.

FIG. 8 demonstrates another inventive embodiment of key server 140 inwhich refresh keys are sent by Multicast rather than point-to-point. Inblock 810, a number of requests are received from several clients. Asdiscussed above, the number of requests are randomly distributed over aninitial keying period before the event starts. Blocks 820, 830, and 840are similar to FIG. 5 wherein a point-to-point secure link isestablished, credentials are verified, and the initial key istransmitted to each authored requesting agent.

In block 850, the embodiment in FIG. 8 deviates from the embodiment inFIG. 5. In FIG. 5, the client initiates refresh requests. In theembodiment of FIG. 8, the key server determines which of the number ofagents remain authorized for the next event interval based on theforward security window in block 850. In block 850, the key servermulticasts the keys to the clients that remain authorized. Any number ofmulticasting techniques can be used. By “pushing” the refresh keys tothe clients rather than pulling them (as in FIG. 5 above) the key serverdoes not have to spend time waiting for refresh requests, establishingindividual point-to-point connections, etc. In block 870, if there areno more additional event intervals, the process ends. If there areadditional event intervals, the process loops back to block 850 to sendthe next multicast key based on the forward security window.

FIG. 9 demonstrates one inventive embodiment of a client system as itinteracts with the ticket server and the key server. In block 910, theclient sends a request to the ticket server. In block 920, the clientreceives a ticket back from the ticket server if the client isauthorized to access the ticket server. In block 930, the clientprovides information taken from the ticket to a user. For instance,using an application program interface (API) to a graphical userinterface, a user can view a representation of the events for which theclient is eligible.

In block 940, the client receives a selection from the user. Theselection indicates one or more of the events from the ticket. Asdiscussed above, for each event, the ticket may include an identifier ofthe event, an IP address of the sender client, an IP address of the keyserver for the event, and a start time for the event.

In block 950, the client generates a random time during the initialkeying interval and, in block 960, sends a request for a key to the keyserver at the random time. The request includes the identifier of theevent and credentials to authenticate access authority. As discussedabove, for sending clients, the time synchronization is importantbetween the sending client and the key server.

In block 970, the client receives a key from the key server. If theclient is a sending client, the key is used to encrypt the data. If theclient is a receiving client, the key is used to decrypt data. In block980, the client participates in the event by sending and/or receivingdata. In block 990, the client continues to participate using refreshkeys as long as the client remains authorized. The keys can be refreshedeither point-to-point or multicast. For point-to-point, refresh requestsare sent at a random time during a first event interval and then atregular intervals thereafter. Of course, as discussed above, inalternate embodiments the time for requests can be randomly generatedfor each event interval. For multicast, refresh keys are pushed toclients for each event interval until, for instance, the client is nolonger authorized, the event ends, or the client indicates that it nolonger wishes to participate.

FIG. 10 demonstrates one inventive embodiment of a procedure forupdating and maintaining the data. In, one embodiment, the procedure isperformed by a management server such as management server 160 ofFIG. 1. In block 1010, the management server waits for a newinstruction. When a new instruction is received in block 1020, themanagement server identifies the instruction. In the illustratedembodiment, an instruction can be an instruction to add a new client,generate a ticket, provide a key, add a new event, delete a client orevent, and modify a client or event. In block 1030, the managementserver identifies parameters for the instructions, such as client,event, and/or group identifiers, credentials for accessing a key, andnew information for modifying old information. In block 1040, themanagement server processes the instruction and waits for a nextinstruction.

FIG. 11 illustrates one inventive embodiment of management server 160including ticket server 130 and key server 140 in greater detail. In theillustrated embodiment, the severs 130 and 140 comprise a backend of themanagement server 160. An application specific front end 1110 handlesclient contact through network 150. Front end 1110 can represent any ofa number of applications including a variety of e-commerce webapplications, a virtual network interface for a private virtual network,etc. For instance, in one embodiment, application front end 1110provides an e-commerce site where sending clients can post amateur audiocontent and receiving clients can listen to the audio content. Sendingclients register with front end 1110 and submit events of audio data. Aspart of the registration process, the front end 1110 determines to whichgroup or groups the sending client and the sending clients audio contentshould be added based on a classification of the audio content. Theregistration process can also include arrangements for payment, such ascredit card approval, biographical information, etc.

Front end 1110 issues commands to the ticket server 130 through gatewayapplication program interface (API) 1120. The commands, once they passthrough gateway API 1120, are in a format usable by server 130 to managedata in the database. The commands may take the form of the commandsdescribed with reference to FIG. 10 previously. That is, commands toadd, delete, and modify the contents of the database, such as thedatabase illustrated in FIG. 3.

In FIG. 11, the servers 130 and 140 are shown both having access to thesame database 1130. In the illustrated embodiment, the database can beused to store authorization relationships among clients and events aswell as keys for accessing the various events. In alternate embodiments,such as those discussed above, the database is accessed and maintainedby the ticket server alone. The key server maintains a separate databasefor matching requests for keys to particular events where, for instance,the key server is separately located for security purposes, and/ormultiple key servers are used, each key server corresponding to only asubset of the total number of events.

FIG. 12 demonstrates one inventive embodiment a security agent forimplementing data security between two network entities, such assymmetric cryptographic keying. As discussed above, various embodimentsof the inventions rely on symmetric cryptographic keying. A standardizedsecurity protocol, Internet Protocol Security (IPsec), can be used toperform the functions needed for the various embodiments of theinventions. Unfortunately, IPsec is not yet widely available, andupgrading existing systems to provide IPsec support is costly and timeconsuming. The embodiment illustrated in FIG. 12 provides the neededsecurity functionality at lower cost and increased simplicity.

The embodiment illustrated in FIG. 12 can be widely used for performingsecurity operations on data between two network entities. The securityagent is not limited to the networking environment described above withreference to FIG. 1, although it can be used in such an environment. Aswith other figures described herein, alternate embodiments may notrequire all of the elements, may include one or more additionalelements, and may combine one or more elements shown in FIG. 12.

FIG. 12 demonstrates the functions of one security agent. A securityagent works in concert with another security agent to provide symmetricnetwork communications. That is, a sending agent applies one or moretransformations to data and a receiving agent applies inversetransformations to reproduce the original data. In one embodiment, usinga pair of security agents, “plaintext” data is transformed into“ciphertext” data, sent over a network, and transformed back intoplaintext data.

In block. 1210, the security agent receives data. In block 1220, thesecurity agent searches the data for selector data. Depending on whetherthe data is outbound or inbound, selector data could include an IPaddress to which the data is directed, an IP address from which the datais received, a port to which the data is directed, and/or a port fromwhich the data was received. Selector data can also include a tag in asecurity header, a failure to pass an integrity check, etc. If noselector data is found, the security agent presumes that the data is notrelated to the security agent's functions and passes the data alongunchanged in block 1270.

If selector data is found in block 1220, the security agent then triesto create a selector from the selector data. A selector is part of aselector/security association pair otherwise known as keyinginformation. For instance, as described above, when a client obtains akey from a key server, the key comprises a selector/security associationpair that is to be used by both a sending client and a receiving clientto secure participation in the corresponding event. The selectorindicates what data should be operated on (namely the event data) aswell as what security association should be used (in particular whichencryption key should be used). In various embodiments, securityassociations are not limited strictly to encryption and decryption.Security associations may call for encryption, decryption, integritycheck, or no action at all beyond removing any special packaging addedto the data. One or more selectors/security associations pairs may bestored and applied to one or more events.

If the selector is not successfully created in block 1230, the data isprevented for going further in block 1280. This may happen where certainselector fields are detected in the data, but the data within thosefields has been corrupted.

If, in block 1230, the selector is successfully created, the selectorcan be used to search a database that stores one or moreselector/security association pairs to identify the correspondingsecurity association in block 1240. If in block 1250 no correspondingsecurity association is found, the data is prevented from proceeding inblock 1280. Without a security association corresponding to theselector, the security agent cannot properly act on the data. Passingthe data may cause various unintended consequences including systemcrashes.

If however, in block 1250, a corresponding security association wasfound, the security agent applies the security association to the datain block 1260. In block 1270, the data is passed along.

FIG. 13 illustrates one embodiment of a security agent 1310 operatingbetween the network API layer 1305 and network protocol layer 1315. Datatraffic from an application (not shown) that is intended for network 150goes through network API layer 1305 and arrives at security agent 1310in the form of a data-gram 1330. If security agent 1310 can identify aselector in data-gram 1330 and identify a corresponding securityassociation in database 1350, security agent 1310 will apply thesecurity association to data-gram 1330. In the illustrated embodiment,the result is data packet 1335 which includes a special security headerand security payload. The security payload includes the encrypted datagram, padding, a security trailer, and a digest.

The data packet 1335 goes through network protocol layer 1315 as if itwere regular data, and is placed in data packet 1345. IP layer 1320fragments the data as needed, attaches IP headers, and sends the dataonto network 150.

For inbound traffic, IP layer 1320 reassembles the data and strips offthe IP headers. Network protocol layer 1315 strips off its header andpasses the data packet 1335 to security agent 1310. Assuming securityagent 1310 is able locate a corresponding security association indatabase 1350 based on a selector created from the data, security agent1310 reverses any security operations on the data. If no selector isfound, then no security operations were done to the data so nooperations need to be reversed.

The operations of security agent 1310 are transparent to the network API1305 and the network protocol layer. The security agent works completelyindependent of the network or the application based on selector/securityassociations previously stored in database 1350.

Where the security agent of FIGS. 12 and/or 13 is used in combinationwith the networking environment of FIG. 1, the database ofselector/security association pairs is populated by a client when theclient access key server 140 and receives keying information.

FIG. 14 illustrates one embodiment of a hardware system intended torepresent a broad category of computer systems such as personalcomputers, workstations, and/or embedded systems. In the illustratedembodiment, the hardware system includes processor 1410 coupled to highspeed bus 1405, which is coupled to input/output (I/O) bus 1415 throughbus bridge 1430. Temporary memory 1420 is coupled to bus 1405. Permanentmemory 1440 is coupled to bus 1415. I/O device(s). 1450 is also coupledto bus 1415. I/O device(s) 1450 may include a display device, akeyboard, one or more external network interfaces, etc.

Certain embodiments may include additional components, may not requireall of the above components, or may combine one or more components. Forinstance, temporary memory 1420 may be on-chip with processor 1410.Alternately, permanent memory 1440 may be eliminated and temporarymemory 1420 may be replaced with an electrically erasable programmableread only memory (EEPROM), wherein software routines are executed inplace from the EEPROM. Some implementations may employ a single bus, towhich all of the components are coupled, or one or more additional busesand bus bridges to which various components can be coupled. Thoseskilled in the art will be familiar with a variety of alternate internalnetworks including, for instance, an internal network based on a highspeed system bus with a memory controller hub and an I/O controller hub.Additional components may include additional processors, a CD ROM drive,additional memories, and other peripheral components known in the art.

In one embodiment, the one or more of the inventive embodiments, asdescribed above, is implemented using one or more computers such as thehardware system of FIG. 14. Where more than one computer is used, thesystems can be coupled to communicate over an external network, such asa local area network (LAN), an IP network, etc. In one embodiment, thepresent invention is implemented as software routines executed by thecomputer(s). For a given computer, the software routines can be storedon a storage device, such as permanent memory 1440. Alternately, asshown in FIG. 15, the software routines can be machine executableinstructions 1510 stored using any machine readable storage medium 1520,such as a diskette, CD-ROM, magnetic tape, digital video or versatiledisk (DVD), laser disk, ROM, Flash memory, etc. The series ofinstructions need not be stored locally, and could be received from aremote storage device, such as a server on a network, a CD ROM device, afloppy disk, etc., through, for instance, I/O device 1450. Theinstructions may be copied from the storage device into temporary memory1420 and then accessed and executed by processor 1410. In oneimplementation, these software routines are written in the C programminglanguage. It is to be appreciated, however, that these routines may beimplemented in any of a wide variety of programming languages.

In alternate embodiments, the present invention is implemented indiscrete hardware or firmware. For example, one or more applicationspecific integrated circuits (ASICs) could be programmed with the abovedescribed functions of the present invention. In another example, thepresent invention could be implemented in one or more ASICs onadditional circuit boards and the circuit boards could be inserted intothe computer(s) described above. In another example, field programmablegate arrays (FPGAs) or static programmable gate arrays (SPGA) could beused to implement the present invention. In yet another example, acombination or hardware and software could bemused to implement thepresent invention.

Thus, a method and apparatus for network content management isdescribed. Whereas many alterations and modifications of the presentinvention will be comprehended by a person skilled in the art afterhaving read the foregoing description, it is to be understood that theparticular embodiments shown and described by way of illustration are inno way intended to be considered limiting. Therefore, references todetails of particular embodiments are not intended to limit the scope ofthe claims.

1-20. (canceled)
 21. An apparatus for facilitating Internet-basedcontent distribution in which events are transmitted among clientsincluding sending clients and receiving clients, the apparatuscomprising a computer processing unit that facilitates retrieval of anevent summary for a client, the event summary identifying a set ofevents for which said client is eligible, the computer processing unitbeing operable to receive a request for the event summary and,responsive to receiving said event summary request, derive the eventsummary from a hierarchical database comprising groups, wherein eachgroup can be assigned one or more clients and one or more events, andwherein the hierarchical database comprises a directed acyclic groupstructure in which clients assigned to a particular group are eligiblefor events assigned to that particular group as well as for eventsassigned to all ancestor groups thereof, the computer processing unitsending the derived event summary to said client.
 22. The apparatus ofclaim 20, in which the computer processing unit is further operable toidentify a first group within said hierarchical database to which theclient is assigned, add all events assigned to said first group to saidevent summary, identify all ancestor groups of said first groupaccording to said directed group structure of said hierarchicaldatabase, and add all events assigned to each of said ancestor groups tosaid event summary.
 22. The apparatus of claim 20, further comprisingmeans for authenticating the client, and wherein said computerprocessing unit is further operable to send, for each event listed insaid event summary, (i) a starting time for the event, (ii) an addresscorresponding to the sending client for the event, and (iii) an addressof a key server for providing one or more symmetric encryption keys forthe event.
 23. The apparatus of claim 20, wherein said events areunicast events.
 24. The apparatus of claim 20, wherein said events aremulticast events.
 25. A computer program product embodied on amachine-readable medium for facilitating retrieval of an event summaryfor a client in an Internet-based content distribution environment inwhich events are transmitted among clients, the clients includingsending clients and receiving clients, the event summary identifying aset of events for which the client is eligible, the computer programproduct comprising: computer code for receiving a request for the eventsummary; computer code for deriving, responsive to receiving said eventsummary request, the event summary from a hierarchical databasecomprising groups, wherein each group can be assigned one or moreclients and one or more events, and wherein the hierarchical databasecomprises a directed acyclic group structure in which clients assignedto a particular group are eligible for events assigned to thatparticular group as well as for events assigned to all ancestor groupsthereof; and computer code for sending the event summary to the client.26. The computer program product of claim 25, wherein said computer codefor deriving further comprises: computer code for identifying a firstgroup within said hierarchical database to which the client is assigned;computer code for adding all events assigned to said first group to saidevent summary; computer code for identifying all ancestor groups of saidfirst group according to said directed group structure of saidhierarchical database; and computer code for adding all events assignedto each of said ancestor groups to said event summary.
 27. The computerprogram product of claim 25, further comprising computer code forauthenticating the client, wherein said computer code for sendingincludes computer code for sending, for each event listed in said eventsummary, (i) a starting time for the event, (ii) an addresscorresponding to the sending client for the event, and (iii) an addressof a key server for providing one or more symmetric encryption keys forthe event.
 28. The computer program product of claim 25, wherein saidevents are unicast events.
 29. The computer program product of claim 25,wherein said events are multicast events.
 30. A system for facilitatingretrieval of an event summary for a client in an Internet-based contentdistribution environment in which events are transmitted among clients,the clients including sending clients and receiving clients, the eventsummary identifying a set of events for which the client is eligible,comprising: means for receiving a request for the event summary; meansfor deriving, responsive to receiving said event summary request, theevent summary from a hierarchical database comprising groups, whereineach group can be assigned one or more clients and one or more events,and wherein the hierarchical database comprises a directed acyclic groupstructure in which clients assigned to a particular group are eligiblefor events assigned to that particular group as well as for eventsassigned to all ancestor groups thereof; and means for sending the eventsummary to the client.
 31. The system of claim 30, wherein said meansfor deriving further comprises: means for identifying a first groupwithin said hierarchical database to which the client is assigned; meansfor adding all events assigned to said first group to said eventsummary; means for identifying all ancestor groups of said first groupaccording to said directed group structure of said hierarchicaldatabase; and means for adding all events assigned to each of saidancestor groups to said event summary.
 32. The system of claim 30,further comprising means for authenticating the client, wherein saidmeans for sending further comprises means for sending, for each eventlisted in said event summary, (i) a starting time for the event, (ii) anaddress corresponding to the sending client for the event, and (iii) anaddress of a key server for providing one or more symmetric encryptionkeys for the event.
 33. The system of claim 30, wherein said events areunicast events.
 34. The system of claim 30, wherein said events aremulticast events.